Process for production of adipic acid from 1,6-hexanediol

Abstract

Processes are disclosed for the conversion of 1,6-hexanediol to adipic acid employing a chemocatalytic reaction in which 1,6-hexanediol is reacted with oxygen in the presence of particular heterogeneous catalysts including at least one of platinum or gold. The metals are preferably provided on a support selected from the group of titania, stabilized titania, zirconia, stabilized zirconia, silica or mixtures thereof, most preferably zirconia stabilized with tungsten. The reaction with oxygen is carried out at a temperature from about 100° C. to about 300° C. and at a partial pressure of oxygen from about 50 psig to about 2000 psig.

We claim: 
     
       1. A process for preparing an adipic acid product, the process comprising chemocatalytically converting 1,6-hexanediol to the adipic acid product by a method comprising reacting the 1,6-hexanediol with oxygen in the presence of a heterogenous catalyst comprising gold and platinum on a support, wherein the support is selected from the group consisting of silica, carbon, zirconia, titania, metal oxide-composite and mixtures thereof. 
     
     
       2. A process for preparing an adipic acid product, the process comprising reacting 1,6-hexanediol and oxygen in the presence of a heterogeneous catalyst comprising gold on a support, wherein the support is selected from the group consisting of silica, carbon, zirconia, titania, alumina, metal oxide-composite and mixtures thereof, and wherein the weight percent of gold to the total weight of the finished catalyst is from about 0.1 wt % to about 10 wt %. 
     
     
       3. The process of  claim 1 , wherein the heterogeneous catalyst comprises a support, the outer surfaces of the support comprising a material selected from the group consisting of zirconia, stabilized zirconia, zirconia-metal or -metal oxide composites, titania, stabilized titania, titania-metal or -metal oxide composites, silica and mixtures thereof. 
     
     
       4. The process of  claim 2 , wherein the surface area of the support is equal to or less than about 220 m 2 /g and the average pore diameter is at least about 5 nm. 
     
     
       5. The process of  claim 3 , wherein the support is a zirconia or stabilized zirconia support and further comprises tungsten. 
     
     
       6. The process of  claim 1 , wherein the heterogeneous catalyst comprises a support selected from the group consisting of zirconia, stabilized zirconia, stabilized zirconia-metal or zirconia-metal oxide composite, titania, stabilized titania, stabilized titania-metal or titania-metal oxide composite, and mixtures thereof. 
     
     
       7. The process of  claim 5 , wherein the tungsten is present in an amount ranging from about 1 wt % to about 15 wt % of the total weight of the support. 
     
     
       8. The process of  claim 6 , wherein the support has a surface area equal to or less than about 220 m 2 /g and an average pore diameter of at least about 5 nm. 
     
     
       9. The process of  claim 6 , wherein the support has a surface area equal to or less than about 100 m 2 /g and an average pore diameter of at least about 10 nm. 
     
     
       10. The process of  claim 1 , wherein reacting the 1,6-hexanediol with oxygen in the presence of the heterogeneous catalyst comprises:
 a) combining the 1,6-hexanediol and the heterogeneous catalyst, and optionally a solvent; and 
 b) contacting the combined 1,6-hexanediol and heterogeneous catalyst, and optionally the solvent, with oxygen. 
 
     
     
       11. The process of  claim 1 , wherein reacting the 1,6-hexanediol with oxygen in the presence of the heterogeneous catalyst and, optionally a solvent comprises:
 a) combining the 1,6-hexanediol and the heterogeneous catalyst, and optionally a solvent, at a temperature equal to or less than about 120° C. ; and 
 b) contacting with oxygen the combined 1,6-hexanediol and heterogeneous catalyst, and optionally the solvent. 
 
     
     
       12. The process of  claim 1 , wherein reacting the 1,6-hexanediol with oxygen in the presence of the heterogeneous catalyst comprises:
 a) combining the 1,6-hexanediol and a solvent; 
 b) contacting the combined 1,6-hexanediol and solvent with a heterogeneous catalyst; and 
 c) contacting the combined 1,6-hexanediol, solvent, and heterogeneous catalyst with oxygen. 
 
     
     
       13. The process of  claim 11 , wherein the solvent is selected from the group consisting of water, alcohols, ethers, and mixtures thereof. 
     
     
       14. The process of  claim 1 , wherein reacting the 1,6-hexanediol with oxygen in the presence of the heterogeneous catalyst and water comprises:
 a) contacting the 1,6-hexanediol with water; 
 b) contacting the 1,6-hexanediol and water with the heterogeneous catalyst; and, 
 c) contacting the combined 1,6-hexanediol, water, and heterogeneous catalyst with oxygen. 
 
     
     
       15. The process of  claim 3 , wherein the reaction is conducted under a partial pressure of oxygen ranging from about 50 psi to about 2000 psi. 
     
     
       16. The process of  claim 3 , wherein the partial pressure of oxygen ranges from about 50 psig to about 1000 psig. 
     
     
       17. The process of  claim 1 , wherein the reacting the 1,6-hexanediol with oxygen in the presence of a heterogeneous catalyst is carried out at a temperature ranging from about 100° C. to about 180° C. 
     
     
       18. The process of  claim 4 , wherein the reacting the 1,6-hexanediol with oxygen in the presence of a heterogeneous catalyst is carried out at a temperature ranging from about 135° C. to about 165° C. 
     
     
       19. The process of  claim 1 , wherein the catalyst further comprises palladium. 
     
     
       20. The process of  claim 1 , wherein the ratio of platinum to gold is from about 10:1 to about 1:1. 
     
     
       21. The process of  claim 1 , wherein the total weight percent of platinum and gold is from about 0.2 wt % to about 5 wt % of the total weight of the catalyst. 
     
     
       22. The process of  claim 1 , wherein the total weight percent of platinum and gold is equal to or less than about 4 wt % of the total weight of the catalyst. 
     
     
       23. The process of  claim 2 , wherein the total weight percent of gold is from about 0.2 wt % to about 5 wt % of the total weight of the catalyst. 
     
     
       24. The process of  claim 2 , wherein the total weight percent of gold is equal to or less than about 4 wt % of the total weight of the catalyst. 
     
     
       25. The process of  claim 1 , wherein the support is selected from the group consisting of silica, carbon and zirconia. 
     
     
       26. The process of  claim 2 , wherein the support is selected from the group consisting of silica, carbon and zirconia. 
     
     
       27. The process of  claim 11 , wherein the solvent is water.